The invention relates to coolant filtration in a machine which has a pump and tank unit for supplying pressurized coolant to the machine, and wherein the coolant supply line is connected to a commercial coolant filter. The commercial filter has inlet and outlet ports for coolant, and a flushing port for removing particulates contamination from the coolant.
The invention is especially usable in systems in which the expected particles comprise metal granules, and identifiable flakes or chips, such as those produced in turning and milling machines.
One commercial filter unit to which the invention is particularly well suited is the LAKOS In-Line Separator, available from Lakos Separators U.S.A., 1911 N. Helm, Fresno, California 93703 which is a centrifugal unit where incoming coolant is swirled through a helical path which causes the particulates contaminants to drop to the bottom of the unit, at a flushing port.
In order to properly flush this commercial filtration unit, the manufacturer has suggested several methods and apparatus for flushing the unit: (a) an on/off air-operated or direct solenoid-operated gate valve, for periodic flushing; (b) a pinch valve, for example, one having an air-operated rubber diaphragm adjustable to permit a small continuous bleed of contaminants with periodic automatic purge when the valve is pulled to the full-open position; and (c) a constant-bleed fixed orifice.
The aforementioned prior art devices are deemed unsatisfactory because of problems encountered in use; the powered valving units are susceptible to clogging, wear, and malfunction of the moving parts, and the fixed orifice restrictor is susceptible to clogging.